Chida K, Yamada S, Kato N, Kuroki T
Department of Cancer Cell Research, Institute of Medical Science, University of Tokyo, Japan.
Cancer Res. 1988 Jul 15;48(14):4018-23.
Activation of protein kinase C (PKC) and the resulting phosphorylations of proteins in vivo were examined in mouse epidermis, a target tissue of tumor-promoting phorbol diesters, such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Treatment of mouse skin with TPA caused rapid translocation of PKC from the cytosol to the membrane fraction of skin tissue, followed by its down regulation. Epidermal proteins were labeled locally with 32P using the ring-shaped forceps technique that economizes on the amount of 32Pi required. Treatment with TPA in vivo resulted in about 2-fold increases in the phosphorylations of epidermal proteins with molecular weights of 34,000 and 40,000 and isoelectric points of 4.7-5.1 and 5.2-6.2 (p34 and p40, respectively). The phosphorylations of these proteins were also stimulated by teleocidin B. Inhibitors of PKC, such as chlorpromazine, quercetin, and staurosporine inhibited these increases in phosphorylations of p34 and p40 on TPA treatment. Furthermore, p34 and p40 were phosphorylated by purified PKC in a cell-free system. These results indicate that p34 and p40 are phosphorylated by PKC in mouse epidermis in vivo and may be involved in tumor promotion.
在小鼠表皮（一种肿瘤促进剂佛波酯如12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯（TPA）的靶组织）中检测了蛋白激酶C（PKC）的激活及体内蛋白质的磷酸化情况。用TPA处理小鼠皮肤会导致PKC迅速从胞质溶胶转移至皮肤组织的膜部分，随后其表达下调。使用节省所需32Pi量的环形镊子技术对表皮蛋白进行局部32P标记。体内用TPA处理导致分子量分别为34,000和40,000、等电点分别为4.7 - 5.1和5.2 - 6.2（分别为p34和p40）的表皮蛋白磷酸化增加约2倍。这些蛋白的磷酸化也受到杀鱼菌素B的刺激。PKC抑制剂如氯丙嗪、槲皮素和星形孢菌素可抑制TPA处理后p34和p40磷酸化的增加。此外，在无细胞体系中，纯化的PKC可使p34和p40磷酸化。这些结果表明，在小鼠表皮中，p34和p40在体内被PKC磷酸化，可能参与肿瘤促进过程。
